I had a regular P365 that was smooth as butter to cycle, I purchased an XL upper assembly to put on it, and noticed it has like a "zipper" type feeling racking the slide. I can see and feel very rigid turn lines on the smaller part of the guide rod that is causing this, whereas the same part in my regular 365 is perfectly smooth. Anyone else run into this? I'd like to polish the guide rod but I'm not sure how or if its able to be taken apart? Im guessing one end screws off?